Absorption characteristics of impact vibration absorbers

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Abstract

This research deals with passive vibration control of a primary mass using impact vibration absorbers (IVA). Primary mass is the structure for which the vibrations are to be mitigated. Different types of IVAs have been proposed, studied and used in practical applications. This research is on two types of IVAs, namely, simple IVA and compound IVA. In simple IVA the impact mass hangs from a pendulum not connected to the primary mass. In compound IVA the impact mass hangs from a pendulum connected to the primary mass.
The first objective of this research was to compare the effect of the pendulum arm length on the absorption characteristics of the simple and compound IVA. The second objective was to determine the effect of the mass ratio, excitation amplitude, and clearance between impact walls on absorber efficiency of the compound IVA model.
For transient vibration involving compound IVAs it was shown that the longest pendulum was more efficient than the shortest pendulum. The largest clearance was more efficient than the smallest clearance. For the largest initial displacement the vibrations were attenuated faster than for the smallest initial displacement. For forced vibrations, the simple IVA (compare to the compound IVA) has a more pronounced inefficient absorption region. This is due to the apparent shift of the resonance point. On the other hand the compound IVA hardly has a clear inefficient absorption region. In the respective absorption region, it is noted that the single IVA has a more prominent vibration absorption level. It was also noted that for the simple IVA the shortest pendulum length is the most efficient, while for the compound IVA the shortest pendulum length is the least efficient.